RFR: 8271118: C2: StressGCM should have higher priority than frequency-based policy [v2]

[Vladimir Kozlov]

On Mon, 26 Jul 2021 07:06:30 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> I think StressGCM should have higher priority than frequency-based policy, otherwise StressGCM has no chance to choose because the frequency-based policy would choose block first if appropriately.
>
> Yi Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   is_cheaper_block

src/hotspot/share/opto/gcm.cpp line 1144:

> 1142:   }
> 1143: 
> 1144:   if (!StressGCM) {

It could be simplified so you don't need to check `if (!StressGCM)`:

  if (StressGCM) {
    // Should be randomly accepted in stress mode
    return C->randomized_select(cand_cnt);
  }

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PR: https://git.openjdk.java.net/jdk/pull/4865